Uncontrolled Memory Allocation Affecting h2o package, versions *
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-ECHOLATEST-H2O-18011551
- published18 Jul 2026
- disclosed10 Jul 2026
Introduced: 10 Jul 2026
NewCVE-2026-55213 (opens in a new tab)How to fix?
There is no fixed version for Echo:latest h2o.
NVD Description
Note: Versions mentioned in the description apply only to the upstream h2o package and not the h2o package as distributed by Echo.
See How to fix? for Echo:latest relevant fixed versions and status.
h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1, when h2o processes a QPACK instruction sent from the peer over HTTP/3, lib/http3/qpack.c might allocate an on-stack buffer as large as approximately 800 KB by calling alloca, which exceeds the default pthread stack size used by musl libc and causes the h2o server to crash with a segmentation fault while touching the guard page. This issue is fixed in commit edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1.